Psychophysical studies of vision in Retinitis Pigmentosa patients and normal control observers are proposed to assess the effects of the receptor degeneration upon the visual capacities of the patients. The underlying assumption of this work is that the remnant cone cell photoreceptors although abnormal do transduce light stimuli to neural information which itself can be abnormal in a number of ways. These abnormalities can have great significance for the perception of light by the patient; and, as far as the patient is concerned, the real significance of Retinitis Pigmentosa is its perceptual consequences. These effects of the degeneration will be assessed in psychophysical measures of: iconic memory and visible persistence, the speed at which visual determinations can be made, distance perception, and visual imagery. These measures will be made in various locations of the visual field chosen on the basis of the sensory capacities of the field area. The sensory capacities will be determined with: static and kinetic perimetry, light and dark adapted threshold sensitivity, spectral sensitivity, the photochromatic interval and flicker fusion. The overall aim of this research is to obtain information to lay the foundation for the development of training procedures which will increase the usefulness of the remaining visual and perceptual capacities of the patient, and provide understanding of the nature of the visual perceptions in the patients so as to provide meaningful counseling and patient management.